These objects are available in all modules. The following variables may appear to be global but are not. They exist only in the scope of modules, see the module system documentation:
The objects listed here are specific to Node.js. There are built-in objects that are part of the JavaScript language itself, which are also globally accessible.
A utility class used to signal cancelation in selected Promise
-based APIs.
The API is based on the Web API AbortController
.
const ac = new AbortController();
ac.signal.addEventListener('abort', () => console.log('Aborted!'),
{ once: true });
ac.abort();
console.log(ac.signal.aborted); // Prints True
reason
{any} An optional reason, retrievable on theAbortSignal
'sreason
property.
Triggers the abort signal, causing the abortController.signal
to emit
the 'abort'
event.
- Type: {AbortSignal}
- Extends: {EventTarget}
The AbortSignal
is used to notify observers when the
abortController.abort()
method is called.
reason
: {any}- Returns: {AbortSignal}
Returns a new already aborted AbortSignal
.
delay
{number} The number of milliseconds to wait before triggering the AbortSignal.
Returns a new AbortSignal
which will be aborted in delay
milliseconds.
The 'abort'
event is emitted when the abortController.abort()
method
is called. The callback is invoked with a single object argument with a
single type
property set to 'abort'
:
const ac = new AbortController();
// Use either the onabort property...
ac.signal.onabort = () => console.log('aborted!');
// Or the EventTarget API...
ac.signal.addEventListener('abort', (event) => {
console.log(event.type); // Prints 'abort'
}, { once: true });
ac.abort();
The AbortController
with which the AbortSignal
is associated will only
ever trigger the 'abort'
event once. We recommended that code check
that the abortSignal.aborted
attribute is false
before adding an 'abort'
event listener.
Any event listeners attached to the AbortSignal
should use the
{ once: true }
option (or, if using the EventEmitter
APIs to attach a
listener, use the once()
method) to ensure that the event listener is
removed as soon as the 'abort'
event is handled. Failure to do so may
result in memory leaks.
- Type: {boolean} True after the
AbortController
has been aborted.
- Type: {Function}
An optional callback function that may be set by user code to be notified
when the abortController.abort()
function has been called.
- Type: {any}
An optional reason specified when the AbortSignal
was triggered.
const ac = new AbortController();
ac.abort(new Error('boom!'));
console.log(ac.signal.reason); // Error('boom!');
If abortSignal.aborted
is true
, throws abortSignal.reason
.
See {Blob}.
- {Function}
Used to handle binary data. See the buffer section.
Stability: 1 - Experimental.
A browser-compatible implementation of ByteLengthQueuingStrategy
.
This variable may appear to be global but is not. See __dirname
.
This variable may appear to be global but is not. See __filename
.
Stability: 3 - Legacy. Use
Buffer.from(data, 'base64')
instead.
Global alias for buffer.atob()
.
See {BroadcastChannel}.
Stability: 3 - Legacy. Use
buf.toString('base64')
instead.
Global alias for buffer.btoa()
.
clearImmediate
is described in the timers section.
clearInterval
is described in the timers section.
clearTimeout
is described in the timers section.
Stability: 1 - Experimental.
A browser-compatible implementation of CompressionStream
.
- {Object}
Used to print to stdout and stderr. See the console
section.
Stability: 1 - Experimental.
A browser-compatible implementation of CountQueuingStrategy
.
Stability: 1 - Experimental. Enable this API with the
--experimental-global-webcrypto
CLI flag.
A browser-compatible implementation of {Crypto}. This global is available
only if the Node.js binary was compiled with including support for the
node:crypto
module.
Stability: 1 - Experimental. Enable this API with the
--experimental-global-webcrypto
CLI flag.
A browser-compatible implementation of the Web Crypto API.
Stability: 1 - Experimental. Enable this API with the
--experimental-global-webcrypto
CLI flag.
A browser-compatible implementation of {CryptoKey}. This global is available
only if the Node.js binary was compiled with including support for the
node:crypto
module.
Stability: 1 - Experimental. Enable this API with the
--experimental-global-customevent
CLI flag.
A browser-compatible implementation of the CustomEvent
Web API.
Stability: 1 - Experimental.
A browser-compatible implementation of DecompressionStream
.
A browser-compatible implementation of the Event
class. See
EventTarget
and Event
API for more details.
A browser-compatible implementation of the EventTarget
class. See
EventTarget
and Event
API for more details.
This variable may appear to be global but is not. See exports
.
Stability: 1 - Experimental. Disable this API with the
--no-experimental-fetch
CLI flag.
A browser-compatible implementation of the fetch()
function.
Stability: 1 - Experimental. Disable this API with the
--no-experimental-fetch
CLI flag.
A browser-compatible implementation of {FormData}.
- {Object} The global namespace object.
In browsers, the top-level scope is the global scope. This means that
within the browser var something
will define a new global variable. In
Node.js this is different. The top-level scope is not the global scope;
var something
inside a Node.js module will be local to that module.
Stability: 1 - Experimental. Disable this API with the
--no-experimental-fetch
CLI flag.
A browser-compatible implementation of {Headers}.
The MessageChannel
class. See MessageChannel
for more details.
The MessageEvent
class. See MessageEvent
for more details.
The MessagePort
class. See MessagePort
for more details.
This variable may appear to be global but is not. See module
.
The perf_hooks.performance
object.
- {Object}
The process object. See the process
object section.
callback
{Function} Function to be queued.
The queueMicrotask()
method queues a microtask to invoke callback
. If
callback
throws an exception, the process
object 'uncaughtException'
event will be emitted.
The microtask queue is managed by V8 and may be used in a similar manner to
the process.nextTick()
queue, which is managed by Node.js. The
process.nextTick()
queue is always processed before the microtask queue
within each turn of the Node.js event loop.
// Here, `queueMicrotask()` is used to ensure the 'load' event is always
// emitted asynchronously, and therefore consistently. Using
// `process.nextTick()` here would result in the 'load' event always emitting
// before any other promise jobs.
DataHandler.prototype.load = async function load(key) {
const hit = this._cache.get(key);
if (hit !== undefined) {
queueMicrotask(() => {
this.emit('load', hit);
});
return;
}
const data = await fetchData(key);
this._cache.set(key, data);
this.emit('load', data);
};
Stability: 1 - Experimental.
A browser-compatible implementation of ReadableByteStreamController
.
Stability: 1 - Experimental.
A browser-compatible implementation of ReadableStream
.
Stability: 1 - Experimental.
A browser-compatible implementation of ReadableStreamBYOBReader
.
Stability: 1 - Experimental.
A browser-compatible implementation of ReadableStreamBYOBRequest
.
Stability: 1 - Experimental.
A browser-compatible implementation of ReadableStreamDefaultController
.
Stability: 1 - Experimental.
A browser-compatible implementation of ReadableStreamDefaultReader
.
This variable may appear to be global but is not. See require()
.
Stability: 1 - Experimental. Disable this API with the
--no-experimental-fetch
CLI flag.
A browser-compatible implementation of {Response}.
Stability: 1 - Experimental. Disable this API with the
--no-experimental-fetch
CLI flag.
A browser-compatible implementation of {Request}.
setImmediate
is described in the timers section.
setInterval
is described in the timers section.
setTimeout
is described in the timers section.
The WHATWG structuredClone
method.
Stability: 1 - Experimental. Enable this API with the
--experimental-global-webcrypto
CLI flag.
A browser-compatible implementation of {SubtleCrypto}. This global is available
only if the Node.js binary was compiled with including support for the
node:crypto
module.
The WHATWG DOMException
class. See DOMException
for more details.
The WHATWG TextDecoder
class. See the TextDecoder
section.
Stability: 1 - Experimental.
A browser-compatible implementation of TextDecoderStream
.
The WHATWG TextEncoder
class. See the TextEncoder
section.
Stability: 1 - Experimental.
A browser-compatible implementation of TextEncoderStream
.
Stability: 1 - Experimental.
A browser-compatible implementation of TransformStream
.
Stability: 1 - Experimental.
A browser-compatible implementation of TransformStreamDefaultController
.
The WHATWG URL
class. See the URL
section.
The WHATWG URLSearchParams
class. See the URLSearchParams
section.
- {Object}
The object that acts as the namespace for all W3C WebAssembly related functionality. See the Mozilla Developer Network for usage and compatibility.
Stability: 1 - Experimental.
A browser-compatible implementation of WritableStream
.
Stability: 1 - Experimental.
A browser-compatible implementation of WritableStreamDefaultController
.
Stability: 1 - Experimental.
A browser-compatible implementation of WritableStreamDefaultWriter
.